1. Field of the Invention
The present invention relates to a valve of an aerosol container for example, intended for dispensing a product at an essentially constant flow rate, for example, a cosmetic product. The invention is most particularly suited for dispensing deodorants or hairstyling products, especially lacquers or mousses.
2. Description of the Related Art
Modernly, the problem of variations in performance between the initial use of a container and the final use is encountered in the field of aerosol dispensers. These problems arise, in particular, in devices in which the product is pressurized by means of a compressed gas, especially carbon dioxide or nitrogen dioxide. In such devices, the gas is either directly in contact with the product or isolated from the product by a piston or a bag containing the product. The variations in flow rate and/or pressure are directly associated with the pressure drops inside the container, which inevitably cause a drop in product outlet flow rate.
It is known, as evidenced by EP-A-0,450,990, to provide a regulator inside a valve so as to regulate the outlet flow rate of the dispensed product. Such regulating systems entail, among other things, the use of a calibrated spring, controlling the extent to which an orifice is open or closed, depending on the pressure inside the regulating chamber relative to the set-point pressure imposed by the spring. In operation, a raised pressure in the regulating chamber causes the inlet orifice of the regulating chamber to close until, once a sufficient quantity of product contained in the regulating chamber has been discharged, the pressure in the chamber returns to the nominal pressure. One of the drawbacks associated with such a regulating system stems from the fact that the calibrated spring is arranged in a part of the valve body in communication with the product. The pressure in this part of the valve body is a partial pressure somewhere between atmospheric pressure and the pressure inside the container. Such a pressure depends on the internal pressure of the container and on any pressure drops incurred as far as the product outlet orifice. The pressure also depends on the product contained in the container, particularly on its vapour pressure. Thus, for each new formulation, it is necessary to use a different calibrated spring, which makes the system somewhat inflexible. Furthermore, the means of shutting off the outlet orifice are not secured to the piston, and this results in a less precise flow rate regulation.
FR-A-2,711,973 describes a push-button, in which a regulating system is arranged. The drawbacks of such a system are mainly of two fold. On one hand, the regulating system takes up a significant amount of space in the push-button, which leaves little latitude for designing the supply to the outlet nozzle or the diffusing system and spray mechanism. On the other hand, between uses, the means of shutting off the regulating chamber are in communication with the outside of the container, and therefore with the air, which entails a high risk of the shutter xe2x80x9cstickingxe2x80x9d, especially in the case of products with a high resin content.
Thus, one of the objects of the invention is to produce a flow rate regulating valve which does not have the drawbacks relating to the regulating devices discussed earlier with reference to the devices of the prior art.
In particular, one object of the invention is to provide a valve with a built-in regulating device which is reliable and economical to produce, and in particular, a valve in which the set-point value does not vary according to the product to be dispensed or according to the variations in pressure inside the container on which it is intended to be mounted.
Another object of the invention is to provide a valve to which any kind of dispensing head can be fitted, and which leaves a great amount of latitude in choosing the diffusing characteristics of the head.
According to a first aspect of the invention, these objects are achieved by producing a valve, particularly for an aerosol container, with a valve body that includes an inlet passage communicating with the container and an outlet passage, means for placing the outlet passage in communication with the inlet passage in response to an actuation command, first elastic return means for urging the valve into the closed position, and means for regulating the product outlet flow rate including second elastic return means for supplying a set-point pressure for the regulating means. In this embodiment, the second elastic return means is arranged in a compartment of the valve body isolated from the product, the pressure inside the compartment being equal to atmospheric pressure.
Thus, since the elastic return means is at atmospheric pressure, the set-point imposed is constant irrespective of the formulation, and irrespective of the pressure inside the container. Furthermore, since the closing means associated with the regulating system are situated inside the valve body, that is to say isolated from the outside when the valve is in the closed position, there is no sticking or soiling of the regulating mechanism which therefore remains reliable over time.
Advantageously, the flow rate regulating means includes a regulating chamber arranged between the inlet passage and the outlet passage. The regulating chamber includes an inlet orifice and an outlet orifice. The flow rate regulating means also includes closing (or shut-off) means mounted on the second elastic return means provided for altering the extent to which the inlet orifice and/or outlet orifice is/are open, according to the pressure inside the regulating chamber (in actual fact, inside the part in which the product flows). The second elastic return means is arranged in a compartment of the regulating chamber isolated from the product by a moving piston in direct communication with the outside, and therefore kept at atmospheric pressure. Thus, even in the event of unwanted diffusion past or around the piston, the pressure inside the compartment containing the calibrated spring remains identical to atmospheric pressure.
Advantageously, the moving piston is secured to the first closing means. This plays a part in improving the precision with which the product outlet flow rate is regulated.
In a specific embodiment, the closing means include first means of shutting off the outlet orifice, having an annular skirt borne by the piston and arranged inside the regulating chamber. The position of the annular skirt with respect to the outlet orifice determines the extent to which the outlet orifice is open. The annular skirt is monolithically formed with the piston by molding a thermoplastic such as a polyolefin, especially a polyethylene or a polypropylene.
Advantageously, the moving piston is mounted slidably inside the regulating chamber. The seal between the compartment containing the calibrated spring and the compartment forming the actual regulating chamber is improved by using a flexible diaphragm arranged inside the body of the regulating chamber between the piston and the calibrated spring. As a preference, such a diaphragm is overmoulded or two-shot injection moulded with the body of the regulating chamber. This diaphragm improves the seal between the two compartments of the regulating chamber without appreciably affecting the force exerted on the piston by the second elastic return means.
Also, advantageously, a stop means is provided for maintaining a minimum product outlet flow rate in the event of an overpressure inside the regulating chamber. Thus, the product contained in the regulating chamber can be discharged until the pressure inside the regulating chamber returns to the set-point level imposed by the second elastic return means, thus avoiding any valve blockage.
The closing means may also include second closing means secured to the moving piston for altering the extent to which the inlet orifice of the regulating chamber is open, according to the pressure inside the regulating chamber. The first and second closing means are configured such that when the inlet orifice is in the closed position, the outlet orifice is at least partially open. In this embodiment, the degree of regulation of the valve is further improved because the pressure inside the regulating chamber is also regulated.
In a particular embodiment, the inlet orifice is arranged in the end wall of the regulating chamber, and the outlet orifice is situated in a side wall of the regulating chamber at a predetermined distance from the end wall of the regulating chamber. An annular lip provides the seal between the regulating chamber and the valve body, around the regulating chamber, where the sealing lip is arranged axially between the end wall of the regulating chamber and the outlet orifice. Such an annular lip can be obtained by molding with the regulating chamber.
In a preferred embodiment, the outlet passage is formed of a valve stem secured to the regulating chamber, the regulating chamber being mounted on the first elastic return means, where the valve stem comprises a part that emerges from the valve body and forms an outlet duct that can be placed in communication with the valve body via a passage that passes radially through the valve stem. Alternatively, this may be a valve of the xe2x80x9cfemalexe2x80x9d type intended to take a hollow stem bore by the valve-actuating mechanism.
Advantageously, when the valve is in the closed position, the radial passage is kept opposite a seal located in the upper part of the valve body.
In another preferred embodiment, when the pressure inside the regulating chamber drops below a predetermined value, the closing means shut off the outlet orifice of the regulating chamber in a leaktight manner so as to interrupt the dispensing of product. Thus, any spraying or diffusing whose characteristics might not be satisfactory, due to an insufficient outlet pressure, is prevented.
A second aspect of the invention provides a container for dispensing a product under pressure and equipped with a valve of the first aspect.
Such a container may comprise a body defining a reservoir containing the product to be dispensed, and one end of which is closed by an end wall, the other end being surmounted by the valve. The means of actuating the valve may include a push-button which may exhibit diffusing means for discharging the product. Such a container may be in the form of a flexible bag which may possibly be placed inside a rigid body, a tube or a can.
By way of example, the diffusing means consist of a nozzle, especially a swirl-inducing nozzle, a grating or a porous end piece such as a sinter or an open-cell foam. The product may consist of a hairstyling product such as a lacquer, spray or mousse, a deodorant, or a beauty care product such as a milk, oil, cream or gel.